Red Sheet Vs Blue Sheet

I have to politely disagree, a coin with a score of 60 is uncirculated ergo a coin with a score of 55 or 58 has to be AU and AU+ respectively.
That would make the AU-50 the top grade for an extra fine coin , as far as my understanding of the cross reference of the grades goes
By your reasoning a AU58 is only EF.
Are you trying to say a MS-60 is AU and a ms-63 is AU+

I wouldn't bother trying to compare the two standards, my chart is just a guide, EF Sydney mint sovereigns rarely grade above AU50 but EF florins often make AU58. ANDA standards aren't consistently applied between each series because they measure detail whereas PCGS measures wear.

You're not alone on that, that's why I suggest learning to grade as PCGS does rather than trying to grade as ANDA does then converting the grade - It's very useful to learn PCGS' grading especially when purchasing on-line. Because of their consistency, you can get a pretty good estimation on what to expect from the grade alone in all factors other than colour (for copper), eye appeal and strike, all of which are fairly easy to work out from a photo.

On the other hand when you buy an ANDA graded coin on-line you have no idea of the condition of the surface of the coin and you need a very specific style of photo to be able to work it out from the photo (95% of photos on-line focus on making the coin look good rather than showing the details you need to assess the surface).